Motor control circuit



2 Sheets-Sheet l R. H. HILL ET AL MOTOR CONTROL CIRCUIT Filed Oct. 23 1942 Feb. 4, 1947. R. H. HILL ETAL. 2,415,170

MOTOR CONTROL 0 IRCUIT Filed on. 25, 1942 2 Sheets-Sheet 2 /270 f 72* A f 47196 JR? 9? 42L Q J J 1 22m 1 Zyj Patented Feb. 4, 1947 MOTOR CONTROL CIRCUIT Robert R. Hill and Edward M. Claytor, Anderson, Ind, assignors to General Motors Corporation, Detroit, Mich; a corporation of Delaware Application October 23, 1942, Serial No. 463,130

18 Claims.

This invention relates to remote control by radio of aircraft and other vehicles.

An object of the present invention is to provide electric motor operated means for actuating the steering mechanism and other controls of the airplane and to provide a system of con-- trol therefor whereby the functions of the electric motor operated means may be controlled from a distance. This object-is accomplished by a system of motor control the several functions of which are caused to become operative respectively in response to the operation of relays of a radio receiver which are tuned to different frequencies. The radio transmitter employsa single wave length or carrier wave which is modulated by one, and sometimes two, P9. plurality of -dil'l'erent frequencies corresponding tothe functions to be controlled. In case two f'u'nctions' of'the motor control are to become operative at the same time, the carrier wave is modulated by a frequency combination such that the tuned re lays, which are selected to operate simultaneously, may effectively separate'the modulating wave into its two components. I l

Further objects and advantages 'of the'p'resent' invention "will be 'apparent from the-following description, reference being had to the accompairying" drawings" wherein a preferred" mbodb ment of the present invention is-clearly shown.

{m the drawings:

Pig; 1' isja; wiring diagram of the {control paratus "'at the radio t'rsesmimpgstaum I "Fig. 2 is a wiringdfagrain tr the control apparatus at the radio receiving station,

Fig. 3 is a wiring diagram of the electric motor controlapparatus which functions in cooperation with the radio transmitter shown in Fig. rand the radio receiver shown in Fig; 2'.' r r The motor control system-shown in 3 is for example adaptedto be operated by the: radio transmitter and receiver disclosed in Mirick Patent 1,597,416g granted August 24,- 1926, and shown. in Figs. 1 and 2.

Referring to' Fig. I, a broadcast antenna I0 is connected by a transformer i I with a generator l2 which provides a radio carrier wave. The means for modulating the carrier wave includes a plurality ofvibrators i3, M, l5, l6, l1, lilenergizm bya battery Hi, the circuit of which is con-e trolled by a main switch 20. The vibrators are adiusted independently to dilierent frequencies. These vibrators are connected respectively by push. buttons or keys 23, 24, 25, 25, 21, 28 with transformer primaries 33, 34, 35, 36, 31, 38 whose secondaries 43,. 44, 45, 45, 41, 4aare connected ap-f ill

having the frequency of the vibrator i3 will be superimposed on the carrier wave and the modulated carrier wave will-be radiated from the antenna i0 and will be picked up by antenna of the receiving apparatus located on the airplane. The signal. received by antenna 60 passes to amplifierdetector H which causes the low frequency S nal to pass through the input of a relay apparatus comprising a master tube 62 and a plurality. oi tubes 63,64; 65, 66, BLEBcorresponding'in number to the number of control circuits at; the transmitter. Tuned resonant relays i3, 14,15, 16, [1; i8 are constructed to respond respectively, to the frequency of the vibrators i3, 14:, i5, IS, IT, I8 of the transmitter. These relays are connected in series in the plate circuit of the master tube 62 supplied by B-battery 69, When key 23 is pressed to connect vibrator l3 with radio generator l2, resonant relay l3 responds to control the input circuit of tube 63, the dutputof whichls connected with a secondary'relay 83 which then operatesto close a switch 83a and thus make a connection between a positivexbattery wire I44 and a terminal 93'. Similarly, wheni itey 21 o! the transmitter is pressed, vibrator Wis connected with radio generator 12; and resonant relay H and tubatttunction to efiect th'eresponse of secondary relay 84 and the closing OI'fJthB swittihFMato connect battery lead Ill-with a terminal 94. Similarly, the other keys 25-" through respectively control tuned relays 15' through 18 to cause the tubes through 68, respectively, to'eflecs the operation of secondary relays tfithrough 88, respectively, and the connection 0t batterywire M4 with terminals 95 through as, respectively.

The filamentcelectrodes' or the tubes are energized by batterytlil. A constant negative potential ismaintairied on the grids of tubes 63 through 68 from battery? "connected across the input circuit of each of these tubes to resistances 63a. through 68m The independent resonant relays 13 through H are provided, respectively, with pairs of contacts 13a which are normally open; but, when any particular relay becomes energized, these contact are closed and charge the grids 0t therespective' tubes with positive polan'ty derived from battery 12 causing a plate current to flow in the particular tube and in the secondary relay in the plate circuit to be actuated. Normally when the contacts of the resonant relays are open, the grids are charged negatively;

and, accordingly, there will be zero plate current through that particularly circuit so that a maximum value of plate current will be obtained upon the closing of the contacts of the resonant relays.

While separate batteries are indicated for supplying negative grid bias and positive charging potential, a separate plate battery for the master tube 62 and a separate plate battery for the relay tubes 03 through 68, it will be understood that this is represented for the sake of clearness and that common source of potential may be employed.

As will be described later, it is necessary to operate two modulating vibrators simultaneously in order to effect the operation of two functions of the motor control system simultaneously. For example, the function of the motor control sys tem controlled by vibrator I3 may be required concurrently with the function controlled by vibrator IS; the function controlled by vibrator I4 may be required concurrently with the function controlled by vibrator I6; and the function controlled by vibrator I may be required concurrently with the function controlled by vibrator I0. This means that tuned relays 13 and must operate simultaneously, or tuned relays 14 and 16 must operate simultaneously, or tuned relays and 10 must operate simultaneously. In securing this simultaneous action of these tuned relays, two-conditions are essential. One condition is that the wave form of the resultant E. M. F. derived from the simultaneous operation of two oscillators must approach that of a wave in which instantaneous values of E. M, F. due to each one singly are added algebraically, Such a resultant is obtained by placing the transformer secondaries 43 through 40 in series as shown in Fig. 1. The second condition is that the waves to be combined should be as nearly as possible of pure sine form without harmonics. This condition is approached by using condensers 53 through 53 to tune the circuits electrically to the periods of the oscillators and resonant relays of the receiving apparatus tuned by condenser 13b through 185.

- The terminals 93 through 90 of Fig. 2 appear also at the top of Fig. 3 with the following additional designations: 93 is designated TR, meaning trim motor right or clockwise; 94 is designated 'I'L, meaning trim motor left or counterclockwise; 95 is designated TC to designate the trim motor centering or returning to center position; 96 is designated GY, meaning gyroscope control; 91 is designated SR, meaning servomotor right or clockwise; 98 is designated SL. meaning servomotor left or counterclockwise.

The trim motor and the servomotor and controller therefor will now be described with reference to Fig. 3 in which the heavy lines indicate the armature circuits of the motor I00 and the servomotor I and the series field circuit of the servomotor. Servomotor I00 drives a shaft represented by a dot-dash line IOI. Shaft IDI operates an arm I02 connected by link I03 with mechanism for operating a rudder or elevator or other part of an airplane to be controlled. A cable I04 is connected with arm I02 and passes around a pulley I05 and is attached at I05 to a plate I01 rotatable coaxially with a shaft I08 connected to a metallic arm I09 carrying a metallic contact or roller III) for engaging either of two conductor segments III or H2 or an intermediate insulating segment II3 carried by plate I01, Shaft IDS is operated by a gyro (not shown).

The slack in the cable I04 is taken up by spring II4 connected with pin I06 and with a stationary stud Il5. Pulley I05 is carried by an arm I I6 attached to a shaft II1 driven by an electric motor I20 called a trim motor and carrying a limit swich operating arm H8 and a centering switch operating cam I10. The function of the trim motor is to set a course to be maintained automatically by the gyro.

The trim motor I20 has an armature I2I connected by brush I22 with a pivot I23 for the armature I24 of a relay I25. Armature I24 is urged downwardly by a sprin I25 so that contact I21 on the armature I24 normally engages a contact I20. The relay I25 has a core I29 surrounded by a magnet coil I30 which, when energized, causes armature I24 to be attracted upwardly to cause contact I21 to be separated from contact I28 and to engage contact I3I, Brush I32 is connected with a magnet coil I33 (which controls a brake) and with an armature I34 of relay I35 having a core I39 surrounded by the magnet coil I40 which, when energized, attracts armature I34 against the action of spring I36 and causes contact I31 (on the armature I34) to separate from contact I38 and to engage contact I4I. A wire I42 leading from the plus pole of a battery is connected by switch I43 with the wire I44. The relay contacts I3I and MI are directly connected to wire I44. A shunt field winding I45 is connected between wire I44 and wire I49 connected with wire I45 leading to the minus pole of the battery. Contacts I28 and I38 are connected by wire I41 and variableresistance I48 with wire I49. I

Relay coils I30 and I40 are connected with wire I49 by wires I50 and I5I. Relay coil I30 is connected by wire I52 with resilient blade I53 carrying a contact I54 for normally engaging a contact I55 carried by resilient blade I56 connected by wire I51 with terminal 93, TR. When sending key 23 (Fig. l) is pressed, terminal 93 becomes connected with positive battery lead I44. Therefore relay I30, which isconnected with battery negative lead I46 through wire I50, wire I5I and wire I49, is energized to attract armature I24 upwardly to separate contact I21 from contact I28 and to cause contact I21 to engage contact I3I, thereby causing current to flow from the battery through armature I2I In such direction as to cause arm IIB to move toward the right or clockwise as indicated by arrow IIGR lnrig. 3. So

long as switch 23 is closed clockwise movement of arm III; will continue but not farther than Is determined by a limit switch ina manner to be described. During operation-of the motor I20 a motor brake (not shown) .;is. held dlsengaged against the actionof-abrakeapplying spring (not shown) by an electromagnet whosecoil I33 is thenin circuit with theimotor armature I2I When switch 23'is opened relay I30-is deenergized and the armature I24 returns to the position shown, thereby causing motor armature I2I to be short-circuited and the armature shaft to be brought quickly to rest by dynamic braking. The armature shaft and hence the arm IIB will be held in position by a friction brake which then is permitted to be engaged by a spring since the electromagnet coll I33 is then ineffective. During the first part of the period of deceleration of the armature shaft, the friction brake is Ineffective to assist in stopping because the magnet I33 is sufiiciently energized to overcome the force of the brake spring. During the end of this period, the magnet coil becomes sufficiently deenergized to allow the spring force of the brake to be effective. Then the friction brake can assist dynamic braking. The principal function of the friction brake is to prevent creeping of the armature shaft and of arm H6. The friction brake spring is adjusted so that when the trim motor is normally loaded, the coil I33 can overcome the spring and' release the brake. If key 23 is pressed long enough to cause arm stud II9 to strike blade I53, then contacts I54 and I55 are separated and armature circuit I30 is interrupted and the motor I20 will stop.

Relay magnet I40 is connected by wire I60 with spring blade IGI carrying a contact I62 engaging a contact I63 on a spring blade I64 connected by wire I65 with terminal 94, TL. When sendin key 24 is pressed, terminal 94 will be connected with battery positive lead I44 and relay coil I40 will be energized since it'is connected through wire I'5I to the battery negative lead I46. Then armature I34 will be attracted upwardly to disengage contact I31 from contact I36 and to move contact I31 into engagement with contact I4I, thereby connecting the motor armature I2I with wires I44 and I41 to cause the arm H6 to rotate counter-clockwise or to the left as indicated by arrow II6L in Fig, 3. So long as key 24 is pressed, counterclockwise rotation 'of arm I I6 will continue, and when the key 24 is released rotation will stop. However-if key 24'is" held down long enough for insulated pin II 9' on arm I I to engage blade I'BI, then contact I62'will be separated from contact I63 and the relay I40 will be deenergized and rotation will stop.

The shaft 1 carrying arms "6' and'II8 does not rotate at the same speed as the motor armature 'I2 I, but at a very much reduced speedythere being a train of speed reducing gears (not shown) between armature I'2I and the shaft "1. Shaft II1 carries a cam I10 for engaginga-cam follower I1I carried by resilient' arm I12 which carries a'contact I-13 for engaging a contact I14 carried by arm I56. Cam I10 also-engages a fol lower I15 on a resilient arm I10 which carries a contact I11 for engaging a; contact 116 on arm I64. When arm I la is in the exact central posi-' tion shown, cam I10 permits both pairs of contacts I13, I14 and I11; I10'to be opened. It arm I'l6ha's been movedtoward the right by motor I20, cam I10 will be rotated clockwise to close contacts I11, I18. If it is desired to restore arm II6 to central position fromsome position toward the right of that shown in Fig. 3, the key is depressed thereby causing terminal 95, TC to be connected with battery positive lead I44; therefore relay coil I40 is energized since it is then connected with terminal 95'-thro'ugh wire I60, contacts I62, I'63,'contacts I18, I11, blade I16 and wire I19 leading to terminal 95. Relay magnet coil I40 being energized, motor I20 will rotate arm II6 to rotate counterclockwise to central position. When central position of arm H6 is reached, cam I10 will permit contacts I11, I18 to be separated. Since relay I35 may have a slight time lag, the motor will not immediately come to rest but will cause arm IIG to move slightly to the left of central position and arm H0 slightly to the right and the cam I10 will so move as to cause contacts I13, I14 to be engaged whereupon relay coil I becomes energized while the magnetic flux in relay I is decaying. Relay I30 being energized, the motor will rotate clockwise and arm I65 will move toward the right, thereby causing contacts I13 to be disengaged, but since relay I30 has atime lag, arm

H8 will not stop moving toward the left until it has caused contacts I11, I10 to be engaged. Therefore there will be an oscillatory motion of arms 0 and H1 through a small angle on each side of central position. This oscillatory centering movement will continue so long as the centering switch or key 25 is pressed. The foregoing obtains where extremely close centering is desired. If approximate centering will suflice, then more clearance can be provided between the cam followers I'II, I15 and the cam I10 in the central position of the cam; and there will be no oscillation of the trim motor.

The servomotor I00 comprises an armature I30, a shunt field I8I connected between wire I44 and wire I46 and a series field I82 connected with wire 202 and connected with wtire I46 through a brake magnet coil I83 which performs the same function as brake magnet coil I33 of trim motor I20. Clutch magnet coil I84 is in parallel with the shunt field I8I. Brake coil I83 functions when the motor is operating to overcome a brake spring (not shown). The brake may be either the shoe type or disc type. The clutch magnet coil I84 and the shunt field IOI are operative when switch I43 is closed. Clutch coil I84, when energized, causes a clutch (not shown) to connect the shaft IOI, driven at a reduced speed by the motor I00 through reduction gearing (not shown), with thearms I02 and 245. When the circuit of motor I00- is interrupted to stop the motor, brake magnet coil I83 is inoperative so that the motor-driven shaft IOI is frictionally prevented from creeping. The shunt field IBI and the clutch coil B4 are energized so long as the switch I43 in positive battery lead I42 is closed.

Armature I is connected through a com mutator with-brushes I and I9I connected respectively with the pivots of relay armatures I92 and I93 urged' downwardly by sprin'gsl94 and I95, respectively, and carrying contacts-J93 and I91, respectively, engageable with contacts I93 and I99, respectively, connected with'a wire 200 leading to aresistance unit 201 connected by wire 202 with" series field coil I82.. Armatures I92 and I93 move upwardly toward relay cores 204 and 205, respectively, when their'surrounding magnet coils 206 and 201, respectively, are energized. 'Coils '206-and' 201 are connected by wires 200'and 269 withbattery negative lead I46. A wire 210 is connected with-wire I44 and with contacts 2I 2 and M3 with-which the armaturecarried contacts I96 and I91, respectively, engage, when the armatures I92, and I93, respec-' tively, move upwardly. Contacts 2I2 and 2I3 are connected with contacts" 2 and H5, respectively, adapted'to be engaged by contacts 2I6 and Z'Il, respectively, carried by armatures I92 and I93, respectively, and insulated from said armatures' and from said contacts I96 and I91. Contacts 2 I 6 and 2 I 1 are connected respectively to wires 2I8 and 2 I9 leading to a resistance 220 connected with a Contact 22I normally engaged by a contact 222 carried by bell-crank armature lever 223 which is attracted toward a relay core 2'24 when its surrounding coil 225 is energized. Armature lever 223 carries a contact 225 for engaging a contact 221. Lever 223, which is electrically connected with contacts 222 and 226, is connected by wire 228 with the junction of wire 200 and resistance 20I, the other end of which is connected by wire 229 with contact 221. Thereforeso long ascontacts 226 and 221 are separated, resistance '-2'0I is effective to reduce the C. E. M. F. of the armature and to reduce the speed of the armature. The engagement of contacts HI and 222 provides a circuit connection by which the resistance 220 is placed in parallel with the armature, said paralleling circuit being completed through either set of contacts 2I4, 2I0 or 2I5, H1. The relay coil 225 is a counter E. M. F. coil. It is connected in parallel with the armature I through a pair of normally closed contacts 230 and 23I, the latter being carried by bell crank armature lever 232 which will move toward relay core 253 whenever either of its surrounding magnet coils 231, 238 are energized. One end of coil 231 is connected with terminal SR, 91 and the other end is connected with a terminal 2310,. Likewise the coil 238 is connected between terminal SL, 98 and a terminal 230a. Terminal 231a is connected with a spring blade 240 carrying a contact 24I normally engaging a contact 242' carried by spring blade 243 having its free end located in the path of movement of an insulated pin 244 on an arm 245 driven by shaft IOI. Blade 243 is connected by wire 245 with relay coil 206. Similarly terminal 230a is connected with spring blade 250 carrying a contact 25l normally engaging a contact 252 carried by spring blade 253 having its free end located in the path of movement of the pin 2'44. Blade 253 is connected by wire 255 with relay coil 201.

Terminal GY, 95 is connected by wire 256 with a resistance 260 connected with a gyro-controlled arm I09. Terminal 231a is connected by wire 251' with segment III which is mounted on the plate I01. Terminal 238a is connected by wire 25!? with segment II2 located on plate I01.

The operation of the motor-controlled system will now be described. When it is desired to effeet a direct manual control of the servomotor I00 (not through the use of the gyro) to effect clockwise rotation of motor I00 as indicated by IO0R as shown in Fig. 3, the key 21 is pressed thereby causing the relay 81 to operate to connect terminal 91 with the positive battery wire I44, Fig. 2. This causes the following circult to be established: wire I44, Fig. 2, connected with terminal 91, relay coil 231, normally closed limit switch contacts I, 2'42, wire 245, relay coil 206, wires 208 and 209, negative battery lead I46. Then armature I92 moves up to cause contact I96 to be separated from contact I98 and to engage contact 2I2 and contact 2I0 to move up to engage contact 2I4. The following armature circuit is then established: wire I44, wire 2 I I1, contact 2I2, contact I96, armature I02, brush l90, armature I80, brush ISI, armature I93, contact I91, contact I99, resistance 2'0I, wire 202, series field I82, brake coil I33, negative battery lead I40. The shunt field I8| and the clutch magnet coil I84 are energized by the closing of switch I43. Therefore the motor I80 operates as a compound wound motor to rotate arm I02 in the direction I02R, the power being transmitted by clutch (not shown) which is effective when clutch magnet coil I34 is energized. The motor I00 will continue to rotate in this direction so long as key 21, Fig. l, is closed but not further than determined by the limit switch in a manner to he described. During the running of the motor the brake coil I83 is energized to cause separation of the brake shoes or discs, not shown. When key 21 is opened the brake coil I83 will be deenerglzezl to allow brake parts to be engaged through the action of a spring, thereby assisting in the stopping of the motor and holding the motor armature in its stopped position. If however the key 21 is held down long enough for the arm 245 to carry its pin 244 into engagement with blade 243 and to cause separation of contacts 242 and NI, then coil 206 will be disconnected and armature I 92 will move downwardly under the action of spring I94 to interrupt the circuit from the battery lead I42 to the armature I80.

Hand control of rotation of arm I02 counterclockwise as indicated by arrow I02L is effected in a similar manner, except that key 20 is pressed to cause terminal SL, 90 to be connected with positive battery lead I44 of Fig. 2. In this case relay coil 201 (instead of 200 as in the case of clockwise rotation) is effective to attract armature I93 upwardly to cause contact I91 to be separated from contact I99 and to engage contact 2I3 thereby causing current to flow through the armature I00 in the opposite direction to give counterclockwise rotation. counterclockwise rotation is limited by engagement of pin. 244 of, arm 245 with switch blade 253 to cause separation of contacts 252 and 25L a I As in the case of the trim motor I20, the stopping of the servomotor I00 from either-direction of rotation is hastened chiefly by dynamic brake: ing and the friction .brake released by magnet I03 (when sufliciently deenergized)- assists in.

stopping and then prevents creeping of the armaiture shaft and arm I02.

Whenever operation of the servomotor I00 is eifected by pressing either of the keys 21 01:20 to cause terminals 91 or as to be connected with the battery, then one or the other, of the relay coils 231 or 238 is energized to en'ect the attraction of armature lever 232 to separate contacts 23I from contact 230. Therefore whenever the servomotor is controlled by hand through the keys 21 or; 20, the relay coil 225 is inoperative and contacts HI and 222 remain closed so that the resistance 220 remains in parallel with the armature I00 when either one of the armatures I92 or I93 is up and the ,other one is down. Un-. der these conditions the resistance 220 is a by-. pass around the armature I and the speed of the armature is thereby limited as well as by the eiiect of the resistance '20I in series withthe series field I82., When the servomotor I00:-is controlled bythegyro, neither of the coils 231 or 230 is eilectlve. Therefore contacts 230, 25 remain closed and the coil 225 operates as a counter E. M. E. coil; and voltage thereon will build up to a certain value as the speed ofthe; motor 111-, creases until finally the armature 223 willbe-attracted toward the core 22'4and the. contacts HI and 222 will be separated andthe contacts 226 and 221 will be engaged, thereby rendering both resistances 220 anti-20lineffective,- whereupon there is an abrupt increase inmotor speed. This increase in motor speed is desirable when controlling the servomotor by gyro control.

To obtain gyro control, the operator presses key 25, Fig. 1, thereby connecting positive battery wire I44 with terminal 6'1, 96 which is connected with gyro-controlled arm I09. As long as conductor roller III) is on the dead spot II3 of plate I01, the servomotor I00 will not operate. However, if the plane should swerve from its course there will be relative rotation between the arm I09 and the segments III and II2. If or example the deviation from course would be such as to cause segment III to be engaged by roller Illl, then there will be a connection between terminal 96 and terminal 231a whereupon relay coil 206 will be energized to cause the servomotor to turn the arm I02 in the direction of the arrow l02R. This will effect a pull in a direction to cause clockwise rotation of plate I01 and hence segment III in the R direction untilsuch time as the dead spot I I3 engages the roller IIO. Then the motor I013 stops and the arm I02 remains in a fixed position. If the deviation from course is in the opposite direction such that segment IIZ engages roller IIIl, then terminal 2330 becomes connected with terminal GY, 95, thereby efl'ecting energization for relay coil 20!- thereby causing motor I to rotate the arm I02 counterclockwise or in the direction of arrow I02L thereby effecting counterclockwise rotation of plate I01 in order to bring the dead spot I I3 again into engagement with the roller IIIl. Since there is a certain time lag in the relay system it is evident that the plate I01 must overtravel the roller slightly therefore there will be an oscillation of the arm I02 through an angle approximately 1 so long as the gyro is controlling the servomotor.

During the 1 oscillation. the acceleration of, the servomotor in either direction is insuificient to cause the counter E. M. F. relay 225 to close. Therefore the oscillation occurs at slow speed. Resistor 20I, being in series with the servomotor, prevents destructive peak currents therein as the motor reverses. Oscillation of the servomotor could be avoided by using a wide nonconducting segment I I3; but that would result in wider deviation from the set course than might be desirable.

The gyro controlled arm I05 so controls the servomotor I00 as to automatically maintain the airplane on a definite course either up or down or left or right. It will be understood of course that the rod I03 is adapted to control a rudder or ailerons. To provide for control of both rudder and ailerons, the apparatus shown in Fig. 3 will be duplicated and the radio controller will be equipped for transmitting 12 different frequencies which are picked up by tuned relays in the receiver.

The course which is automatically kept by the gyro controller of the servomotor is established by the trim motor I20. I! for example one wishes to establish a course to the right of the course which had been maintained, the key 23 Is pressed to effect clockwise rotation of arm H5 in the direction of arrow IIGR in the manner which has been described. When the arm IISso moves, the spring H4 auses the plate III! to move counterclockwise to bring the segment III into engagement with the roller III) on the gyro controlled arm I09 whereupon the servomotor I00 will cause the arm I02 to move to the direction I02R to effect a change in course to the right. Arm l09' and its contact 0 are held in fixed relation to the earth by the gyro. Plate I01 is moved by the plane when it deviates trom course, or by the trim motor when desired. The change in course will cause the plate ID! to rotate clockwise relative to the arm I89 until the dead spot H3, hits the roller I 60; then the change in course is thereafter maintained by the gyro. The extent of change in course to the right will depend on the duration of closin of the key 23. Likewise if it is desired to change the course toward the left, the key 24 is pressed to cause the arm H6 to move eountercloekwise as indicated by a1"- row MEL. the: :by clockwise rotation of plate I07 to brim: Il2 into engagement with roller llll, ther by cruising the servomotor Illil to move 111m I02 amine:clockwise as indi cated by arrow I02L. This will change the course to the left and the plate ID! will rotate counterclockwise to carry the dead spot II3 into contact with the roller IIO on gyro arm I09. The extent Lof, change of course to' the left depends upon the duration of closing of switch 24. When either of the switches 23 or 24 are open, the plate I07 remains in the adjusted position set by the trim.motor. Thereafter the gyro controls the servomotor I00 to maintain the, course determined by the trim motor.

The functioningfof the system with respect to changing the course letter to right or to left applies equally well to chang g the angle of flight to up or to down- As stated before, for complete control for ieftand. right and up and down, the system shown in Fig. 3 would be duplicated, one system for direction and the other for angle of flight and the transmitter would provide for sending twelve different frequencies and the receivenwould provide for picking up those frequencies and causing the proper tuned relay. to beresponsive thereto. Obviously the sending and receiving apparatusesmusttake care of at least two frequencies at'the same timesince key 26 of gyro-controller is held down' while either of keys 23, 24, 25 is operated.

Wheneverit is desired to return to the course originally set, the key 25 is pressed while key 25 is pressed to cause the trimmotorj to return to center position, thereby centerlngthe'iarm H6 and the plate I01 thereby' causing the gyro to control the. servomotonro; a course straight drop acrosselther o1 relay coils 206 or 201 is the samewhether'they operate ln serles with coils 231 or. 238, respectively, as in case or direct control of the servomotor I00, or whether they operate in series with the resistanceZBIl, as in case of gyro control otthe servomotor, L I

From the foregolng description of. the construc tion and mode 0! operationbf the'servbmotor control system, it is apparent that'fweprovide for direct manual control-.01 the servo'motor for slow speedoperation in eithendli'cction; is an advantage because thelfewill be lessdanger of gettingtoo muclndevlation'j'rrdm. course by the direct manual ':onti:ol. other words, the manual control is lesssensltivmlanda lesser degree of skill is required to operate it. We have provided gyro automatic .control by which the servomotor maintains a course. During oscillation of theservomotor between close limits, the acceleration o! themotor is low and the motor is protected by a resistaneewhich prevents overheating.- The course to be, maintained by the gyro is determinedby' thetrlm-motor. II the deviation from course is to-be small the adjustment made by the motor is small and the servomotor operates at slow speed. If the deviation from course is relatively great requiring larger adjustment by the trim motor, the servomotor accelerates to top speed in order to eflect its control of the steering apparatus quickly,

To recapitulate, applicants invention relates to a remote control 0! a steering part of a vehicle. For example, applicants invention is adapted to operate and control the adjustment of the rudder of an airplane. An electric servomotor I00 provides the motive power to adjust the rudder. A series of local push buttons are provided of which buttons 27 and 28, when pressed, complete remote controlling circuits for effecting rotation of the motor in one or the other direction respectively. For instance when button 21 is closed the motor operates to adjust the rudder to the right, and when button 28 is closed the motor adjusts the rudder to the left. Limit switches stop motor operation when the rudder has been adjusted through a predetermined range of movement in either direction. The speed of the servomotor during these adjusting cycles is held at a reduced speed by the provision of a relay controlled resistance circuit across the armature of the motor.

During flight of the airplane a gyroscope is adapted to maintain the airplane in a substantially constant direction. When gyro control is to be instituted, push' button 26 is pressed rendering the gyro controlled circuits to the servomotor eiiective. Now any deviation of the airplane from the set course in one direction or the other will cause the gyro control to become effective automatically to cause the servomotor to operate and adjust the rudder in one direction or the other to return the airplane from its veered course to the set course. The relay controlled resistance circuit is opened and thus the motor is adapted to operate at full speed while under gyro control,

The course which is automatically kept by the gyro controller of the servomotor is established by the trim motor I20. If, for example, the operator desires to establish a course to one or the other side of the course then maintained by the gyro, either push button 23 or 24 is depressed while the push button 26 is depressed. When push button 23 is closed the trimmer motor I2ll is caused to rotate in the one direction which will rotate the gyro plate I01 in one direction causing said gyro to become effective to render the servomotor operative to adjust the rudder so that the airplane is now brought into the newly set course in which the gyro will maintain it. To change the course of the airplane to the opposite side of the set course, button 24 is pressed which 45 eflects rotation of the trimmer motor I20 in the other direction, adiusting the gyro so that the servomotor is rendered effective to adjust the rudder for the newly set course in which the airplane is maintained by said gyro. Limit switches control the operation of the trim motor so that it may actuate the gyro adiusting mechanism at a predetermined distance only in either direction.

In the claims which follow, the term automotive vehicle embraces land, water and air vehicles, The term course as applied to air vehicles includes an upwardly or downwardly course as well as a directional course.

While the embodiment of the present invention as herein disclosed constitutes a preferred form. it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, relay switches having magnet coils for causing rotation of the servomotor in opposite directions, a two-way switch for controlling the relay switches and having a gyro-controlled contact and two spaced contacts respectively connected with the magnet coils of the relay switches, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member and manually controlled means for establishing connection between a current source and the relay magnet coils through the two-way switch.

2. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, relay switches having magnet coils for causing rotation of the servomotor in opposite directions, a two-way switch for controlling the relay switches and having a gyro-controlled contact and two spaced contacts respectively connected with the magnet coils of the relay switches, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing connection between a current source and the relay magnet coils through the two-way switch, and manually controlled means for effecting movement of the plate.

3. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, means for connecting a current source with either oi! the devices, means responsive to the operation of a gyro for controlling the connecting means, means responsive to the operation of the servomotor for controlling said connecting means, a reversible trim motor, means for eflecting a control of the connecting means by movements of the trim motor in either direction, and manually controlled means for eilecting operation of the trim motor in either direction.

4. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, relay switches having magnet coils for causing rotation of the servomotor in opposite directions, a two-way switch for controlling the relay switches and having a gyro controlled contact and two spaced contacts respectively connected with the magnet coils of the relay switches, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements oi the steering member, manually controlled means for establishing connection between a current source and the relay magnet coils through the two-way switch, a reversible trim motor, means for effecting movement of the plate in response to movements of the trim motor in either direction, and manually controlled means for effecting operation 01' the trim motor in either direction.

5. A motor control system for use with vehicle steering app ratus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a two-way switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements 01 the steering members, and manually controlled means for establishing a connection between a current source and the electrical devices through the two-way switch.

6. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a. movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the twoway switch, and manually controlled means for moving the plate in either direction.

'7. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices fOr causing rotation of the servomotor in opposite directions, a two-way switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the two-way switch, a reversible trim motor, means for effecting movement of the plate in response to movements of the trim motor in either direction, and manually controlled means for effecting operation of the trim motor in either direction.

8. A motor control system for use with vehicle steering apparatus comprising a. reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, a spring for urging the plate in one direction, a cable connecting the plate with the steering member operated by the servomotor and held taut by the spring, a bodily movable pulley around which the cable passes, manually controlled means for moving the pulley in either direction. and manually controlled means for establishing through the two-Way switch a connection between a current source and the electrical devices which control the servomotor.

9. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation or the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, a sprin for urging the plate in one direction. a cable connecting the plate with the steering member operated by the servomotor and held taut by the spring, a bodily movable pulley around which the cable passes, a reversible trim motor [or mOVlng the pulley in either direction, manually controlled means for effecting operation of the trim motor in either direction, and manually controlled means for establishing through the two-way switch a lICllL nection between a current source and the electrlcal devices which control the servomotol',

10, A motor control system for use with voluclc steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, means for connecting a current source with either of the devices, means responsive to the operation of a gyro for controlling the connecting means, means responsive to the operation of the servomotor for controlling said connecting means, a reversible trim motor, means for efi'ecting a control of the connecting means by movements of the trim motor in either direction, manually controlled means for effecting operation of the trim motor in either direction from a normal status, and manually controlled means for effecting an operation of the trim motor reverse to that just previously efiected and then causing the trim motor to stop after returning to normal status.

11. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices throughout the two-way switch, a reversible trim motor for moving the pulley in either direction, manually controlled means for effecting operation of the trim motor in either direction from a normal status, manually controlled means for effecting an operation of the trim motor reverse to that just previously effected and then causing the trim motor to stop after returning to normal status and manually controlled means for establishing through the two-way switch a connection between a current source and the electrical devices which control the servomotor.

12. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, a spring for urging the plate in one direction, a cable connecting the plate with the steering member operated by the servomotor and held taut by the spring, a bodily movable pulley around which the cable passes, a reversible trim motor for moving the pulley in either direction from an intermediate location, manually controlled means for effecting operation of the trim motor in either direction, manually controlled means for effecting an operation of the trim motor reverse to that just previously effected and then causing the trim motor stop in response to return of the pulley to said intermediate location, and manually controlled means for establishing through the two-way switch a connection between a current source and the rlltlifirlt'lil devices which control the servomotor,

13. A motor control system for use with vehicle steering apparatus comprising a reversible scrvmnolor, a steering member operated thereby. lectrically operated devices for causing rotation of [h servoinotor in opposite directions, a two way 'iWlLCll for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the twoway switch, the spacing between the plate-supported contacts of the two-way switch being relatively short whereby the steering member is given an oscillatory movement by the servomotor which is caused to rotate alternately in opposite directions through control by the two-way switch, and means for preventing the rise of destructive peak currents due to reversals of the servomotor.

14. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a. twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the twoway switch, whereby the two-way switch operates through its gyro-controlled contact and its servomotor operated plate to maintain a course within certain limits, and means for shifting the plate in order to set the control system for changing the course, and means for causing the servomotor to operate at less than full speed when the amount of course change is relatively small or at full speed when the amount of course change is relatively great.

15. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a, gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, .a movable plate supporting the two spaced contacts,means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the twoway switch whereby the two-way switch operates through its gyro-controlled contact and its servomotor operated plate to maintain a course within certain limits, and means for shifting the plate in order to set the control system for changing the course, means for limiting the speed of the servo-motor to less than full speed and means responsive to a predetermined duration of the operation of the servo-motor for rendering inoperative the speed limiting means in order that the servo-motor will operate at full speed, whereby the servo-motor operates at less than full speed when the amount of course change is relatively small or at full speed when the amount of coursechange is relatively great.

16. A motor control system for use with vehicle steering apparatus comprising a reversible servo-motor, a steering member operated thereby, electrically operated devices for causing rotation of the servo-motor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the two-way switch whereby the two-way switch operates through its gyro-controlled contact and its servo-motor operated plate to maintain a course within certain limits, and means for shifting the plate in order to set the control system for changing the course, a servo-motor-armature by-passing resistance circuit for limiting the speed of the servo-motor to less than full speed, and a counter E. M. F. relay connected with the servomotor-armature for rendering said resistance circuit ineffective after a predetermined duration of the operation of the servo-motor in order that the servo-motor will operate at full speed, whereby the servo-motor operates at less than full speed when the amount of course change is relatively small or at full speed when the amount of coursechange is relatively great.

17. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a twoway switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the twoway switch whereby the two-way switch operates through its gyro-controlled contact and its servomotor operated plate to maintain a course within certain limits, and means for-shifting the plate in order to set the control system for changing the course, means for limiting the speed of the servomotor to less than full speed and means responsive to a predetermined duration of the operation of the servomotor for rendering inoperative the speed limiting means in order that the servomotor will operate at full speed, whereby the servomotor operates at less than full speed when the amount of course-change is relatively small or at full speed when the amount 0! coursechange is relatively great, and manually controlled means for directly connecting the electrically operated controlling devices 01 the servomotor with a current source and for rendering inoperative the means which is responsive to a predetermined duration of the servomotor for rendering inoperative the speed-limiting means of the servomotor whereby the servomotor will operate only at reduced speed when only the direct manual control is effected.

18. A motor control system for use with vehicle steering apparatus comprising a reversible servomotor, a steering member operated thereby, electrically operated devices for causing rotation of the servomotor in opposite directions, a two-way switch for controlling the electrical devices and having a gyro-controlled contact and two spaced contacts respectively connected with the electrical devices, a movable plate supporting the two spaced contacts, means for causing the plate to move in accordance with movements of the steering member, manually controlled means for establishing a connection between a current source and the electrical devices through the twoway switch whereby the two-way switch operates through its gyro-controlled contact and its servomotor operated plate to maintain a course within certain limits, and means for shifting the plate in order to set the control system for changing the course, a servomotor-armature by-passing resistance circuit for limiting the speed of the servomotor to less than full speed, and a counter E. M. F. relay connected with the servomotorarmature for rendering said resistance circuit ineffective after a predetermined duration of the operation of the servomotor in order that the servomotor will operate at full speed, whereby the servomotor operates at less than full speed when the amount of course-change is relatively small or at full speed when the amount of coursechange is relatively great and manually controlled means for directly connecting the electrically operated controlling devices of the servomotor with a current source and for rendering inoperative the counter E. M. F. relay whereby the servomotor will operate only at reduced speed when only the direct manual control is effective.

EDWARD M. CLAYTOR.

ROBERT H. I-HLL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,597,416 Mirick Aug. 24, 1926 1,725,600 Sperry Aug. 20, 1929 

